1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1988 AT&T */
28 /* All Rights Reserved */
29
30
31 #pragma ident "%Z%%M% %I% %E% SMI"
32
33 #include <stdio.h>
34 #include <fcntl.h>
35 #include <string.h>
36 #include "symint.h"
37 #include "debug.h"
38
39 /*
40 * symintFcns.c -- symbol information interface routines.
41 *
42 * these routines form a symbol information access
43 * interface, for the profilers to get at object file
44 * information. this interface was designed to aid
45 * in the COFF to ELF conversion of prof, lprof and friends.
46 *
47 */
48
49
50 /*
51 * _symintOpen(aout_name)
52 * aout_name - char string file name of object file
53 * to open.
54 *
55 * returns PROF_FILE * - pointer to the PROF_FILE structure built,
56 * or NULL if fails.
57 */
58
59 /*
60 *
61 * .H 3 "Executable File Open and Close"
62 *
63 * Under COFF, the routine ldopen, given a file name, returns a pointer to a
64 * structure called an LDFILE. This descriptor is then passed to each of
65 * the library routines (such as read header, read symbol table entry, etc)
66 * to access the information contained in the file. These calls are spread
67 * throughout the profiling code.
68 *
69 * Under ELF, the file must be opened using a system open call. The file
70 * descriptor is then passed to a routine which returns a pointer to an
71 * Elf structure. This pointer is then passed along to another routine which
72 * returns a different pointer which is in turn passed along to another
73 * routine. In an attempt to avoid disturbing the current format of the
74 * code (by having to pass around different types of pointers), we plan to
75 * build a PROF_FILE descriptor which will then be passed around in the
76 * same way as the pointer to LDFILE.
77 *
78 * Thus, for ELF, an open will consist of opening the file and extracting
79 * enough from it to fill in the PROF_FILE structure. The code for the
80 * open is as follows; the code for building the symbol table (extracting
81 * information from the sections to fill an array of PROF_SYMBOLS) has
82 * yet to be written.
83 *
84 */
85
86 /*
87 * globals
88 */
89
90
91 static char
92 *fail_open_s = "Unable to open file",
93 *fail_begin_s = "Unable to read (begin) file",
94 *fail_ehdr_s = "Unable to get elf header in",
95 *fail_sec_s = "Unable to get section",
96 *fail_shd_s = "Unable to get header for section",
97 *fail_dat_s = "Unable to get data for section",
98 *fail_sym_s = "Cannot find symbol table section in",
99 *fail_pfsym_s = "Unable to process symbols in",
100 *fail_buf_s = "Data buffer is null for section",
101 *fail_sym32_s = "Cannot handle more than 2^32 symbols"
102 ;
103
104
105 /*
106 * this points at the name of the executable.
107 */
108 static char *executableName;
109
110
111
112 /*
113 * section_data_p() - return ptr to section data,
114 * given section ptr and name of section.
115 */
116
117 static Elf_Data *
section_data_p(Elf_Scn * sec_p,char * str)118 section_data_p(Elf_Scn *sec_p, char *str)
119 {
120 Elf_Data *dat_p;
121
122 if ((dat_p = elf_getdata(sec_p, NULL)) == NULL)
123 _err_exit("%s %s in %s.", fail_dat_s, str, executableName);
124 return (dat_p);
125 }
126
127
128 PROF_FILE *
_symintOpen(char * aout_name)129 _symintOpen(char *aout_name)
130 {
131 /*
132 * Elf file open operation
133 *
134 * - point at executable's name, globally
135 * - open file
136 * - align to current version
137 * - read the elf descriptor and header
138 * - read header-names section descriptor, header, and data
139 * - allocate space for all the section hdrs (pf_shdarr_p).
140 * - set a pointer to the header-names buffer
141 * - search the section headers for
142 * - debug section header and data
143 * - line section header and data
144 * - symbol table header, data, strings, and number of symbols
145 * and copy each section hdr into our array.
146 * - populate the PROF_SYMBOL array and anchor it in (pf_symarr_p).
147 */
148
149 PROF_FILE *pfile_p; /* PROF_FILE ptr to return. */
150
151 Elf *telf_p;
152 Elf_Scn *tscn_p;
153 Elf32_Shdr *tshd_p;
154 int k;
155 Elf64_Xword nsyms_pri = 0, nsyms_aux = 0;
156
157 executableName = aout_name;
158
159 DEBUG_LOC("_symintOpen: top");
160 if (aout_name == NULL) {
161 _err_exit("name of executable is null\n");
162 }
163 DEBUG_EXP(printf("Attempting to open %s\n", aout_name));
164 pfile_p = _Malloc(sizeof (PROF_FILE), 1);
165
166 if ((pfile_p->pf_fildes = open(aout_name, O_RDONLY)) == -1)
167 _err_exit("%s %s.", fail_open_s, aout_name);
168 if ((elf_version(EV_CURRENT)) == EV_NONE)
169 _err_exit("Elf library out of date");
170 if ((pfile_p->pf_elf_p = elf_begin(pfile_p->pf_fildes,
171 ELF_C_READ, (Elf *)NULL)) == NULL)
172 _err_exit("%s %s.", fail_begin_s, aout_name);
173
174 DEBUG_EXP(printf("elfkind = %d\n", elf_kind(pfile_p->pf_elf_p)));
175 if ((pfile_p->pf_elfhd_p = elf32_getehdr(pfile_p->pf_elf_p)) == NULL)
176 _err_exit("%s %s.", fail_ehdr_s, aout_name);
177
178 DEBUG_LOC("_symintOpen: after call to getehdr");
179 telf_p = pfile_p->pf_elf_p;
180
181 tscn_p = elf_getscn(telf_p, k = pfile_p->pf_elfhd_p->e_shstrndx);
182 if (tscn_p == NULL)
183 _err_exit("%s %d in %s.", fail_sec_s, k, aout_name);
184
185 if (elf32_getshdr(tscn_p) == NULL)
186 _err_exit("%s %s in %s.", fail_shd_s, "header names",
187 aout_name);
188 if ((pfile_p->pf_snmdat_p = elf_getdata(tscn_p, NULL)) == NULL)
189 _err_exit("%s %s in %s.", fail_dat_s, "header names",
190 aout_name);
191
192 DEBUG_EXP(printf("Address of data header = 0x%lx\n",
193 pfile_p->pf_snmdat_p));
194 DEBUG_EXP(printf("d_buf = 0x%lx\n",
195 pfile_p->pf_snmdat_p->d_buf));
196 DEBUG_EXP(printf("d_type = %d\n",
197 pfile_p->pf_snmdat_p->d_type));
198 DEBUG_EXP(printf("d_size = %d\n",
199 pfile_p->pf_snmdat_p->d_size));
200 DEBUG_EXP(printf("d_off = %d\n",
201 pfile_p->pf_snmdat_p->d_off));
202 DEBUG_EXP(printf("d_align = %d\n",
203 pfile_p->pf_snmdat_p->d_align));
204 DEBUG_EXP(printf("d_version = %d\n",
205 pfile_p->pf_snmdat_p->d_version));
206
207 if (pfile_p->pf_snmdat_p->d_buf == NULL)
208 _err_exit("%s %s in %s.", fail_buf_s, "header names",
209 aout_name);
210
211 DEBUG_LOC("_symintOpen: after call to getdata (for header names)");
212
213 pfile_p->pf_shdarr_p = _Malloc(pfile_p->pf_elfhd_p->e_shentsize,
214 pfile_p->pf_elfhd_p->e_shnum);
215
216 {
217 #ifdef DEBUG
218 char *shdnms_p = (char *)pfile_p->pf_snmdat_p->d_buf;
219 #endif
220
221 char *dest_p = (char *)pfile_p->pf_shdarr_p;
222 int shdsize = pfile_p->pf_elfhd_p->e_shentsize;
223 int i = 0;
224 int symtab_found = 0;
225
226 tscn_p = 0;
227 DEBUG_EXP(printf("Section header entry size = %d\n", shdsize));
228 DEBUG_EXP(printf("First section header name = %s\n", &shdnms_p[1]));
229 pfile_p->pf_symdat_aux_p = NULL;
230 /*
231 * Scan the section headers looking for a symbol table. Our
232 * preference is to use .symtab, because it contains the full
233 * set of symbols. If we find it, we stop looking immediately
234 * and use it. In the absence of a .symtab section, we are
235 * willing to use the dynamic symbol table (.dynsym), possibly
236 * augmented by the .SUNW_ldynsym, which contains local symbols.
237 */
238 while ((tscn_p = elf_nextscn(telf_p, tscn_p)) != NULL) {
239 if ((tshd_p = elf32_getshdr(tscn_p)) == NULL)
240 _err_exit("%s %d in %s.", fail_shd_s, i, aout_name);
241 i++;
242
243 (void) memcpy(dest_p, tshd_p, shdsize);
244 dest_p += shdsize;
245
246 DEBUG_EXP(printf("index of section name = %d\n",
247 tshd_p->sh_name));
248 DEBUG_EXP(printf("_symintOpen: reading section %s\n",
249 &shdnms_p[tshd_p->sh_name]));
250
251 if (symtab_found)
252 continue;
253 switch (tshd_p->sh_type) {
254 case SHT_SYMTAB:
255 DEBUG_LOC("_symintOpen: found symbol section");
256 pfile_p->pf_symstr_ndx = tshd_p->sh_link;
257 pfile_p->pf_symdat_pri_p =
258 section_data_p(tscn_p, "symtab");
259 nsyms_pri = tshd_p->sh_size / tshd_p->sh_entsize;
260 /* Throw away .SUNW_ldynsym. It is for .dynsym only */
261 nsyms_aux = 0;
262 pfile_p->pf_symdat_aux_p = NULL;
263 /* We have found the best symbol table. Stop looking */
264 symtab_found = 1;
265 break;
266
267 case SHT_DYNSYM:
268 /* We will use .dynsym if no .symtab is found */
269 DEBUG_LOC("_symintOpen: found dynamic symbol section");
270 pfile_p->pf_symstr_ndx = tshd_p->sh_link;
271 pfile_p->pf_symdat_pri_p =
272 section_data_p(tscn_p, "dynsym");
273 nsyms_pri = tshd_p->sh_size / tshd_p->sh_entsize;
274 break;
275
276 case SHT_SUNW_LDYNSYM:
277 /* Auxiliary table, used with .dynsym */
278 DEBUG_LOC("_symintOpen: found dynamic symbol section");
279 pfile_p->pf_symdat_aux_p =
280 section_data_p(tscn_p, "SUNW_ldynsym");
281 nsyms_aux = tshd_p->sh_size / tshd_p->sh_entsize;
282 break;
283 }
284
285 }
286 }
287
288 if (pfile_p->pf_symdat_pri_p == NULL || pfile_p->pf_symstr_ndx == 0)
289 _err_exit("%s %s.", fail_sym_s, executableName);
290
291 pfile_p->pf_nstsyms = (int)(nsyms_pri + nsyms_aux);
292 pfile_p->pf_nstsyms_aux = (int)nsyms_aux;
293 if ((nsyms_pri + nsyms_aux) != (Elf64_Xword)pfile_p->pf_nstsyms)
294 _err_exit("%s %s.", fail_sym32_s, executableName);
295
296
297 DEBUG_LOC("_symintOpen: after for loop that reads the sections");
298
299 DEBUG_LOC("_symintOpen: before call to _symintLoad");
300
301 if ((pfile_p->pf_symarr_p = _symintLoad(pfile_p)) == NULL)
302 _err_exit("%s %s.", fail_pfsym_s, executableName);
303
304 DEBUG_LOC("_symintOpen: after call to _symintLoad");
305
306 /*
307 * At this point we might want to include some consistency
308 * checks to be sure all is well. For example, we can check
309 * symbol table consistency by comparing "the product of the
310 * number of symbols and the size of each symbol" to "the
311 * length of the symbol table data".
312 *
313 * Also, NULL may be a proper value (e.g., the debugger
314 * information when there is none) for some things that
315 * we cannot afford to be without. We should check these
316 * at this point also.
317 */
318
319 DEBUG_LOC("_symintOpen: bottom");
320 return (pfile_p);
321 }
322